For more than a quarter of
a century the AAVSO has sponsored a program for regular observation of a number
of eclipsing binaries for the purpose of tracking changes of period and
updating the ephemerides when necessary.Most of the observations have been made visually, but some individuals
have applied photoelectric photometry to this project, adding a few very
valuable minima to our archives.Here, we limit our discussion to visual observing and examine two
distinct observing strategies for determining times of minima.